Faculty Collaboration Database

Effects of gene replacement therapy with resamirigene bilparvovec (AT132) on skeletal muscle pathology in X-linked myotubular myopathy: results from a substudy of the ASPIRO open-label clinical trial. EBioMedicine 2024 Jan;99:104894

Date

12/13/2023

Pubmed ID

38086156

Pubmed Central ID

PMC10758703

DOI

10.1016/j.ebiom.2023.104894

Scopus ID

2-s2.0-85179618072 (requires institutional sign-in at Scopus site)

Abstract

BACKGROUND: X-linked myotubular myopathy (XLMTM) is a rare, life-threatening congenital muscle disease caused by mutations in the MTM1 gene that result in profound muscle weakness, significant respiratory insufficiency, and high infant mortality. There is no approved disease-modifying therapy for XLMTM. Resamirigene bilparvovec (AT132; rAAV8-Des-hMTM1) is an investigational adeno-associated virus (AAV8)-mediated gene replacement therapy designed to deliver MTM1 to skeletal muscle cells and achieve long-term correction of XLMTM-related muscle pathology. The clinical trial ASPIRO (NCT03199469) investigating resamirigene bilparvovec in XLMTM is currently paused while the risk:benefit balance associated with this gene therapy is further investigated.

METHODS: Muscle biopsies were taken before treatment and 24 and 48 weeks after treatment from ten boys with XLMTM in a clinical trial of resamirigene bilparvovec (ASPIRO; NCT03199469). Comprehensive histopathological analysis was performed.

FINDINGS: Baseline biopsies uniformly showed findings characteristic of XLMTM, including small myofibres, increased internal or central nucleation, and central aggregates of organelles. Biopsies taken at 24 weeks post-treatment showed marked improvement of organelle localisation, without apparent increases in myofibre size in most participants. Biopsies taken at 48 weeks, however, did show statistically significant increases in myofibre size in all nine biopsies evaluated at this timepoint. Histopathological endpoints that did not demonstrate statistically significant changes with treatment included the degree of internal/central nucleation, numbers of triad structures, fibre type distributions, and numbers of satellite cells. Limited (predominantly mild) treatment-associated inflammatory changes were seen in biopsy specimens from five participants.

INTERPRETATION: Muscle biopsies from individuals with XLMTM treated with resamirigene bilparvovec display statistically significant improvement in organelle localisation and myofibre size during a period of substantial improvements in muscle strength and respiratory function. This study identifies valuable histological endpoints for tracking treatment-related gains with resamirigene bilparvovec, as well as endpoints that did not show strong correlation with clinical improvement in this human study.

FUNDING: Astellas Gene Therapies (formerly Audentes Therapeutics, Inc.).

Author List

Lawlor MW, Schoser B, Margeta M, Sewry CA, Jones KA, Shieh PB, Kuntz NL, Smith BK, Dowling JJ, Müller-Felber W, Bönnemann CG, Seferian AM, Blaschek A, Neuhaus S, Foley AR, Saade DN, Tsuchiya E, Qasim UR, Beatka M, Prom MJ, Ott E, Danielson S, Krakau P, Kumar SN, Meng H, Vanden Avond M, Wells C, Gordish-Dressman H, Beggs AH, Christensen S, Conner E, James ES, Lee J, Sadhu C, Miller W, Sepulveda B, Varfaj F, Prasad S, Rico S

Author

Suresh Kumar PhD Associate Professor in the Pathology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Genetic Therapy
Humans
Infant
Male
Muscle Strength
Muscle Weakness
Muscle, Skeletal
Myopathies, Structural, Congenital